Cover will not come up to cut wood

If your saw is completely intact, meaning no missing or damaged parts, the blade guard should rotate out of the way of cutting as the saw head is lowered to make a cut. You didn't give your model number but there should be a push rod or link plate from the pivot point on the base to the blade cover that pushes the guard out of the way as the head is pivotted downward. If you have the cutting head locked down to make sliding cuts the guard should be up and out of the way. If this isn't happening you may have broken or missing parts of the guard system.

Yes, Did you buy it new? It has two heavy plastic seen through plate that are attached to each other. This safety shield is gravity fed. That mean as one pull down the saw the safety guard will pivot into the upper shield. As the saw go back up after cutting a piece of wood. The safety shield will drop back into it safety position covering the 12" blade. GB...stewbsion

you should be able to order one from sears. another place to look is ebay. the round plastic thing is to mark with pencil the cut of the blade. put in your sliding miter Gage set at 90 deg. put a piece of wood on it, push forward and cut the wood then slide back and mark the wood position on the plastic. that's the point where your blade cuts

i cant tell you for sure, but, usually just put a piece of wood on the plate or deck, pull the saw down and have the blade make contact with the wood. tighten the nut and hold downward pressure

The pivot is probably full of pitch or other debris. Clean with turpentine if you work with pine or other resinous woods.

Possible but I would think not likely
Try this
Put a new blade on
Set a magnet on the table or fence with phillips screw driver stuck to it
Slide the point of the screw driver up to within 1/16" from the blade just above the teeth
Run the unplugged saw by hand and watch for any side to side movement of the blade
Can you move the blade up and down or side to side?
If everything seems normal the plug the saw in and run it again watching the screwdriver
Please be careful don't allow the screw driver to contact the blade at high speed you will create a bullet

I assume that your alignment procedure is about adjusting your miter gage. But you should first verify if the blade is parallel to the miter slot (the slot the miter gage slides in). This is adjustable underneath the saw, and sometimes comes crooked from the factory or comes loose later on. To check if the blade is parallel to the miter slot you can do this.....1. unplug the saw. 2. Raise the blade as far as it will go. 3. Clamp a piece of wood to your miter gage so that it just touches the blade as close to the front of the saw as possible. 4. Use a marker and mark that spot on the blade. 5. Now slide the miter toward the back of the saw, and rotate the blade by hand so that your piece of wood hits the same spot as where you checked in the front. You can see a large misalignment by eye. But you can get a little precise by using a piece of paper between the wood and the blade as a feeler gage. Or better yet, use a drop indicator instead of the piece of wood and you can measure the difference. If this isn't as close to parallel as you are able to measure it, you need to turn the saw over and find the bolts that attach the whole assembly under there to the table top. Once you have this in alignment, you should be able to set your miter to be square against any good square. If you don't have a high quality square, you can go to a tool store (Sears or whoever) with your miter gage in hand, and set it to be square against their most expensive square. If the square is square, and the blade is parallel to the slot and it still won't cut square you either have a bad blade or there is too much play in the saw's arbor. Try to wiggle the blade side-to-side - any wiggle at all is too much.

i use a framing square off of the back fence with the blade down. when it is square, i check the other side of the fence and loosen the screws on the plate with the degree increments and set it to zero

Lift the Handle.

There may be a push button type blade lock, and on many of these saws the retaining bolt for the blade is backwards threads, e.i., looking at the top of blade retaining bolt, turn it clockwise to loosen. This would normally tighten, but in the case of many of these saws, it loosens it.